The invention concerns a feed screw for use in sedimentation or treatment systems for clearing suspensions in the paper making industry.
Screws of this type are often in the form of a self-supporting helix, the surface of which extends generally axially. A feed screw is known from DE-A 40 00 150; however, this feed screw is not axleless, but apparently has a shaft through which the helix is driven by a motor.
Treatment systems or sedimentation systems for fiber suspensions, for instance used for recycled paper, involve the risk of accumulations bunching up on the helix due to the existence of long contaminants, such as ribbons, strings, etc.
The problem underlying the invention is to boost the productive output of such a system considerably when a helix without a support axle is used as a feed screw. Such a feed screw has a relatively large clearance in the central area, so as to insure a flawless feeding over long operating periods.